Urban residential development in Singapore has been focussed on clusters of high-rise public housing known locally as 'new towns'. Indoor climatic conditions were assessed in a sample of 214 flats in the new towns. Also a sample of 583 occupants were interviewed about their experiences of thermal comfort. Separate body-environment heat-balances were estimated for each respondent and these data were input to the PMV (ISO 7730) mathematical model of thermal comfort. The operative temperature actually preferred by the respondents was about 1°C cooler than the mean value of 29.6°C recorded in their flats. However, their empirically derived temperature preference was about 2°C warmer than the value predicted by the PMV model and ISO standard. Processes of physiological acclimatization and perceptual habituation are put forward as possible explanations for the discrepancy between temperature climate comfort theory and actual human response in the tropics. The implications for energy conservation in tropical cities are also discussed.